The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, February 18, 2007

How Fast Do Birds Fly?By Ro Wauer

On several occasions the last few weeks, a Cooper’s hawk has zoomed through my back yard where I have a number of bird feeders. A second or two before the hawk appears all of the songbirds utilizing my feeders suddenly explode, dashing for cover in the adjacent brush or oak foliage overhead. They are somehow warned of the approaching hawk, probably by a bird chirp at the outer edge that detected the hawk first. But in at least one instance the Cooper's hawk already had a bird in its talons, probably captured just before passing through.

The hawk's swift flight caused me to wonder about its speed. After all, predators of all kinds, rather birds, mammals, or reptiles, depend upon speed, timing and/or surprise for their survival. A Cooper's hawk is one of the pursuit hawks, often referred to as an accipiter, that can quickly accelerate to 60 mph, although it and the closely related sharp-shinned hawk may fly as slow as 16 to 20 mph. The larger and more common full-time resident red-tailed hawk commonly flies at 20 to 40 mph. The American kestrel, a common wintertime falcon, has a flight speed that varies from 22 to 36 mph. And golden and bald eagles fly from 28 to 44 mph.

The fastest of all birds is the peregrine falcon at over 140 mph, and some claim that a diving peregrine can reach more than 200 mph. This large predator can actually chase down swifts that can fly at more than 100 mph. Peregrines reside through the winter along the Texas coast, and occasionally they are seen 30 to 50 miles inland. Waterfowl and shorebirds are favorite prey species that, even in an accelerated escape mode, are in no way able to escape from the much faster peregrine. Ducks have been recorded to fly from 40 to 65 mph, while a spotted sandpiper, a common wintering shorebird, has been clocked at 25 mph.

Hummingbirds seem to be extremely fast, but that is largely due to their relatively small size. Ruby-throated hummingbirds, the common species that we see daily during the summer months, normally fly at 28 mph, although one was clocked at 50 mph with a tailwind. High-speed photography has been used to time their wing beats at about 70 times per second.

Wing beats also vary considerably, from the 70 per second of hummingbirds to as few as two beats per second for the American crow. Chickadee wing beats average 27, mockingbirds 14, American goldfinches 4.9, European starlings 4.3, eastern bluebirds 3.1, domestic pigeons 3, mourning doves 2.45, and American robins 2.3. And the great blue heron, a huge wader that is common along area waterways and wetlands, barely beats its wings at a rate of one per second. Its normal flight speed had been clocked at 28 mph, but it has the ability to speed up to 45 mph.

But what about the flight speed of the average songbird that we see daily in our yards and fields? Most fly at 15 to 25 mph, but they often can accelerate to about twice that speed for short distances when pursued. The crow, among the most common birds in the Golden Crescent, has a flight speed at 16 to 19 mph; the common house sparrow is one of the slowest at 16 to 19 mph; blue jays normally fly at 20 mph; loggerhead shrikes at 28 mph, American robins at 32 mph, and barn swallows at 60 mph.

A bird's relative flight speed is most evident when it is fleeing from a faster bird. But a predator's speed is often only part of its success. I once watched a Cooper's hawk sitting in a tree overlooking a pond at Guadalupe Mountains National Park where white-throated swifts were drinking. The swifts were making passes over the pond, right to left from the hawk's perspective. After considerable time watching the swifts, the hawk took flight just as a swift was approaching the pond, and its timing was so perfect that it picked off the swift, grabbing it at from a side approach, and flew back to its perch to consume its prey.